Assessing nitrogen and phosphorus efficiency at farm and catchment scale using nutrient budgets

Farm nutrient budgets related to 1994 were calculated for seven farm types, accounting for ∼90% of the agricultural land in the River Ythan catchment, NE Scotland. The magnitude of fluxes of nitrogen (N) and phosphorus (P) at the catchment scale in relation to these farm types was also assessed. Positive budgets were calculated for all farm types, with the largest surpluses estimated for intensive livestock units. Nutrient efficiency, defined as a percentage of outgoing over incoming nutrients, ranged from 11% (N) and 21% (P) on ‘cattle and sheep’ farms in less favoured areas to 54% (both N and P) on ‘cereal’ farms. The contribution from cropping versus livestock farming in the total efficiency varied widely between farm types. At the catchment scale the surplus associated with grassland and livestock (225 and 37 kg ha⁻¹ of N and P) clearly exceeded that associated with arable crops (44 and 19 kg ha⁻¹ of N and P). © 2000 Society of Chemical Industry     

Aerobic bacterial, coliform, Escherichia coli and Staphylococcus aureus counts of raw and processed milk from selected smallholder dairy farms of Zimbabwe

A cross sectional study was conducted to enumerate total viable bacteria (TBC), coliforms, Escherichia coli and Staphylococcus aureus in raw (n = 120) and processed (n = 20) milk from individual farms from three smallholder dairy schemes of Zimbabwe between October, 2009 and February, 2010. Data on management factors were collected using a structured questionnaire. A standard pour plate technique was used to enumerate total viable bacteria, while for coliforms, E. coli and S. aureus, counts were assessed by the spread plate technique. The association of total viable bacterial counts and management factors was assessed using univariable and a linear regression model. The log₁₀ TBC for raw milk differed significantly (P < 0.05) amongst the schemes with the lowest (5.6 ± 4.7 log₁₀ cfu/ml) and highest (6.7 ± 5.8 log₁₀ cfu/ml) recorded from Marirangwe and Nharira respectively. The mean log₁₀ of TBC of processed milk (6.6 ± 6.0 log₁₀ cfu/ml) were marginally higher than those of raw milk (6.4 ± 5.6 log₁₀ cfu/ml) but not significant (P > 0.05). The coliform, E. coli and S. aureus counts for raw milk significantly differed (P < 0.05) amongst the study areas. The variation in TBC, coliforms, E. coli and S. aureus counts amongst the schemes could be attributed to differences in milking hygiene where farms with more access to training and monitoring of microbiological quality of milk had lower counts. Linear regression analysis revealed dairy scheme, delivery time and season of milking as independently associated with increased TBC of raw milk. The high TBC of raw and processed milk generally indicated low levels of milking hygienic practices, and high level of post-processing contamination, respectively. The high TBC, coliform, E. coli and S. aureus counts of both raw and processed milk may present a public health hazard. Thus, educating the farmers on general hygienic practices, quickening the delivery of milk to collection centres, or availing cooling facilities on-farm will improve the microbiological quality and safety of milk.     

Browsing the Real World using Organic Electronics,Si‐Chips,and a Human Touch

Organic electronics have been developed according to an orthodox doctrine advocating “all‐printed’’, “all‐organic’’ and “ultra‐low‐cost’’ primarily targeting various e‐paper applications. In order to harvest from the great opportunities afforded with organic electronics potentially operating as communication and sensor outposts within existing and future complex communication infrastructures, high‐quality computing and communication protocols must be integrated with the organic electronics. Here, we debate and scrutinize the twinning of the signal‐processing capability of traditional integrated silicon chips with organic electronics and sensors, and to use our body as a natural local network with our bare hand as the browser of the physical world. The resulting platform provides a body network, i.e., a personalized web, composed of e‐label sensors, bioelectronics, and mobile devices that together make it possible to monitor and record both our ambience and health‐status parameters, supported by the ubiquitous mobile network and the resources of the “cloud”.     

Hydrogen-induced CO2 formation from ethylene deposits on Pt during consecutive O2 and H2 exposures

The oxidation of C₂H₄ deposits on polycrystalline Pt when exposed to consecutive O₂ and H₂ pulses at room temperature has been investigated in a long (L = 36 mm), shallow (d = 600–700 nm) micromachined glass–SiO₂–Pt channel. Hydrogen-induced CO₂ formation from species accumulated on the Pt surface was observed. Frequent switching of the O₂/H₂ exposure pulses was found to increase the efficiency of the oxidation of the carbonaceous deposits markedly. The observations may be of general interest for the regeneration of contaminated catalysts.